Electrical circuits for motor vehicles



April 4, 1950 s. A. MCMILLAN ELECTRICAL CIRCUITS FOR MOTOR vsnxcussFiled June 16, 1945 S x k w k INVENTOR.

Sherman ,4.MM///ar7 BY ATTORNEY Patented Apr. 4, 1950 UNITED STATESPATENT OFFICE ELECTRICAL CIRCUITS; FOR Moron VEHICLES Sherman A.McMillan, San Francisco, Calif;

Application June 16, 1945, Serial No. 599,826 3 Claims. (01. 123-179)Ifhe present invention relates to improvements in electrical circuitsfor motor vehicles, including sea and aircraft, and its principal objectis to introduce certain safety features whereby fire hazards aresubstantially eliminated.

, For this purpose it is principally proposed to provide means wherebythe main battery circuit 7 starter switch to again close the separateswitch,

in order that the latter when open, remains unaffected by the mereclosing of the ignition switch.

And finally, I propose to provide means whereby the separate switch ismade to remain closed, after the starterswitch has been released, aslong as the conventional ignition switch remains closed.

It is a still further object of my invention to provide against firehazards due to collision and due to the overturning of the motorvehicle, by causing a break in the main ground circuit of the battery,whereby the entire electrical system is rendered inactive and all dangerof shorts is eliminated.

Further objects and advantages of my invention will appear as thespecification proceeds, and the novel features of my electrical circuitwill be fully defined in the claims hereto attached.

The preferred form of myinvention is illustrated in the accompanyingdrawing forming part of this application, in which:

The one figure shows a wiring diagram illustrating my circuit.

While I have shown only the preferred form of the invention, it shouldbe understood that various changes or. modifications may be made withinthe scope of the claims hereto attached without departing from thespirit of the invention.

Referring to the drawing in detail, the conventional storage battery Iis shown as being connected, on the positive side, to the starting motor2 through wire 3.

At the motor, the wire divides into two branches, one passing throughthe starter switch 4 and the motor windings to the ground, as at 5,while the other is the main electrical circuit and includes the wire 6,armature 6, the switch 1, which is normally open, the wire 1', the windings 8 of an overloadsolenoid, a movable switch member 9 which normallycontacts a stationary switch member ID, and a wire ll leading to theammeter l2.

Beyond the ammeter the ignition circuit comprises a wire [3,the'conv'entio'nal ignition switch l4 and wire [5 leading to theignition coil primary and thence to the ground, in the conventionalmanner.

The negative side of the battery is connected to the ground, asindicated at |6,'through wire II which contains the switch 18, normallyclosed.

One of the principal features of the present invention is the switch 1,which is normally open,

and which breaks the main electrical circuit,

preferably near the battery, unless it has been closed by operation ofthe starter switch.

The starter switch 4 is connected, through wire l9, with a relay =20,grounded as at 2|, which latter closes, when energized, a switch 22, ina line 23 leading from wire I!) to the solenoids 24 and the ground, asat 25. The solenoids, when energized, close the switch I, so that thelatter is closed whenever the starter switch is depressed for startingthe engine.

Assuming that the operator, before pressing the starter switch, hasclosed his ignition switch, the solenoids 24 will continue to be fed,for maintaining. switch 1 closed after the starter switch has beenreleased, through wire 26, which leads from the ignition switch past thegas gauge 21 to the wire 23 and the solenoids.

When the ignition switch is opened, switch I automatically opens, and itremains open, even if the ignition switch is closed thereafter. Theswitch 1 is only closed when the starter switch is operated andthereupon is maintain in closed position through current flowing throughthe ignition switch, so that it remains closed as long as the ignitionswitch is closed.

In case it is desired to operate equipment, such as light or radio,while the vehicle is standing idle and the ignition switch is turnedoff, I provide a shunt circuit 28 for the switch 1, the shunt preferablyincluding a fuse 29 and a switch 30 subject to manual control.

In case of accident and collision of the motor vehicle, shorts naturallydevelop, causing a heavy flow of current through the overload solenoid8,

This solenoid is designed to become active at a predetermined overload,soas to break the switch 9l0 and to move switch member 9 into contactwith a switch member 35, closing a circuit leading from the battery Ithrough wires 3, 6, 1', and thence through wire 36 to a solenoid relay3'! and the ground, as at 38.

The overload solenoid has a .lock-outsdevice 8 comprising two dogs .60engaging in a grooveS-i for holding the armature 9 in contact withcontact 35.

Since the breaking of the switch 9l0 would allow switch 1 to open, Iprovide- 'a fuse-t? across the contacts to maintain current flow throughl l, I2, i3, i4, 26, 23 to solenoid 2'4 for a .briefperiod which willkeep switch 'I closed until switch H! has opened, as described in thenext paragraph.

The solenoid 31 closes a switch 39, which causes a current to flow fromwire 6 through wires 40, 4| and 42 to the solenoid 43 and the battery.through wire 11. The solenoid breaks the'switch |8,thus opening the mainelectrical connection-J for the battery to the frame. "The core of thesolenoid is held in switch-opening position by a "pair of "hinged dogs64 engaging in the indentations 55. The latter connection is furtherprotected against a 'heavy' surge of current by a thermostat controlincluding a bimetallic strip 46, which opens -a switch (notshown) incase'of excessive heat.

"The circuit last" describedmaysalsobe used for closing a'valve-iiinthefuel line 49 coming'from the'gas tanka50 through aleveroperated'by a solenoid'52forming part of a shuntcircuit :53

branching off from .wire 4|, and grounded asat 5'4.

' To guard against fire hazards due to overturning of the motor vehicle,I provide amercury switch 55 shunted across'switch l, and connected by'wires'56' and 5l,'to wires 40' and 36, respec- "tively.

In case the motor vehicle overturns; the mercuryswitchcloses; andcausesa current .to flow ,from' the: battery I through the solenoid31,0105- xiing switch 39 and breaking the mainrbattery "groundconnection at I8.

After a'collision, if the engine should continueto"keep'running'the'generator shown at 58, I in- "troducea relative lowamperage fuse59, responsive toabout six amperes, in thegeneratorifieldcircuit, which will render thengenerator inoperative when the fuse burnsout.

Where magneto-ignition is used, as in airplanes '.or any system usingdualignitionora combination of battery .andmagneto ignitionjl use thevarmature'ii to operate a second contact "70 and push it againstinsulated contactll, jther'eby grounding line 12 leading to aninsulatedmember of breaker contacts'flii on the magneto or, batteryprimary "M on the magneto armatureili.

"When'the primary is thus ,groundedonboth .sides, no spark .will beinduced ,in the secondary "winding. Switch IO-H ,might be .used in "thesame 'manner to short circuit the vprimarycircuit of aconventionaldistributor.

I claim:

1. .In an. electric circuit for. a.,motor vehicle,- a 7 source ofelectrical energy, an ignition switch, a line connecting the vsourcewiththe ignition switch and having" a safety switch therein; an electromagnetfor operating the safety switch,

..i ngea.,b.atte1y, a starting motor with a starting :switch, anzammeter, an electrical lighting system and an ignition system, thecircuit comprising a main lineconnecting the positive side of thebattery to the lighting system and having the am- ;meterincorporatedtherein, a branch line con- :nected to the main line below the ammeterand leading,tovtheuignition system, an ignition switch in said branchline, a normally open safety switch in the main line between the batteryand the ammeter and having an electro-magnet for closing the same, asecond branch line connected to the main line between the battery andthe safety switch andhaving the starting-switch therein and'beingiconnecte'd to the electro-magnet for closingthe safetysw-itchwhen the-starting switch is 'closed, and athird branch line connected tothe first branch line-below the ignition switch and tot-heelectro-magnet for maintaining the safety 'switch closed as long asthe ignition switch is closed,-but allowing the safetyswitch to openwhen the ignition switch is opened.

3. An electrical circuit fora motor vehicle having a battery, a startingmotor with a starting switchan ammeter, anelectrical lighting-system andan ignition system, the circuit comprising a main line connecting thepositive'side'of the battery to the lighting systemandhaving-the am--meter-incorporated therein, a'branch line connected to the main linebelow the ammeter and leading to the ignition system, an ignition switch:Jin said branchiline, a normally opensafety switch in: the'mainline-betweenthebattery and theam- "meter and having: anelectro-magnetfor closing the same, a-second'branch line connected to the "main linebetween the battery andthe-safety switch and having the starting switchtherein :and being connected to the electro-magnet for -closing-thesafety switch when the starting switch ."is closed, and athird'branch-line connected to the first branch'line'below the ignition switchand to the ,electro-magnet for maintaining the safety switch c10sed;as';l0ngas the ignition switch is "closed,;'but allowing the safety switchto open *whenthe. ignition; switch ;is opened, the-second branch-line-havin g a relay between the starter and the electroemagnet toprotect the starter from current flowing "through the "third branchline.

SHERMAN A. 1 MCMILLAN.

REEERENGES CITED The, following'references' are of-record in the file ofthispatent:

UNITED STAT-ES PATENTS

